no-weld pulse jet

Moderator: Mike Everman

stfx
Posts: 6
Joined: Thu Jul 29, 2004 10:26 pm
Antipspambot question: 0
Location: Canada

no-weld pulse jet

Post by stfx » Thu Jul 29, 2004 10:32 pm

I don't know if any of you have seen the updated verson of the no weld pulse jet, the one that uses the stainless steel drink flask, well I was wondering just how Bruce does this, I was itrested in making one,but since he rarly updates the stuff, im having a hard time piecing together the project so i could build it myself, so I was wondering if any of you out there could describe this step by step how to build one.

btw: Im not gonna atempt to buy his cd or book since i have read many complaintes on the forum.

Mark
Posts: 10754
Joined: Sat Oct 11, 2003 10:14 pm

Post by Mark » Thu Jul 29, 2004 11:57 pm

Essentially, if you have a necking body and an exhaust tube of some sort, you can bang out a pulsejet. The little one inch diameter pulsejet I bought recently uses this philosophy. A flared exhaust tube is pulled through the body until it catches on the neck and tightened or press pulled into place. It's also the philosophy used on the tiny 6.5 inch pulsejet for sale now on eBay it looks like.
The tricky part is to get a good round seal where the head, (you have to make), fits into the combustion chamber. Rounding out a piece of aluminum can be done by rotating the disk against a grinding wheel with a nail or something in the center of the disk so that you can keep it registered a certain distance from the grinding wheel. Any extra metal will be rounded off as you rotate the head around a point.
Here is an almost exact volumetric replication of the Dynajet body and exhaust tube without the head. It's an auto fuel additive can and length of pipe that has been flared, you slip the non-flared end in the additive can and pull it through until the flare locks in the neck. Then you can flare the tail end too, the exhaust end. A neat thing would be to make a collapsible pulsejet you could slink open and closed like a pirate's telescope. I have a gleaming stainless steel collapsible cup and have always wanted to make a compact pulsejet that telescopes out like an antenna.
You can find copper fittings at a hardware store and make a pulsejet out of the necking bells and half inch exhaust piping or whatever size tubing you want to use. Copper will probably hold up for short runs or if you cool the jet with water once it starts. Copper fittings are dirt cheap too.
Mark
Attachments
040118105738.jpg
(366.52 KiB) Downloaded 1757 times

Mike Everman
Posts: 4930
Joined: Fri Oct 31, 2003 7:25 am
Antipspambot question: 0
Location: santa barbara, CA
Contact:

Post by Mike Everman » Fri Jul 30, 2004 12:19 am

That additive can is aluminum though, isn't it? You know the vessels we need, I finally realize are "flasks". There's plenty of aluminum ones with threaded mouths, but I wonder if they make SS.
Mike
__________________________
Follow my technical science blog at: http://mikeeverman.com/
Get alerts for the above on twitter at: http://twitter.com/mikeeverman

Mark
Posts: 10754
Joined: Sat Oct 11, 2003 10:14 pm

Post by Mark » Fri Jul 30, 2004 12:21 am

Here's an odd collection of coppery fittings and the shapes you can make, the large chrome object with some of the chrome polished off revealing the copper underneath, the shape is something you would see if you were standing in front of a urinal. It's the necking shape if you recognize it. I bought it at a scrap yard. There are also some iron objects, the things threaded at one end that also tapper down. The smallest copper fitting is a 1/2 inch bell reducing to a 1/4 inch size if you can pick it out of the jumbled mass. I didn't spend any time composing the picture.
Mark
Attachments
040729184855.jpg
(646.84 KiB) Downloaded 1625 times

Mark
Posts: 10754
Joined: Sat Oct 11, 2003 10:14 pm

Post by Mark » Fri Jul 30, 2004 12:28 am

Mike Everman wrote:That additive can is aluminum though, isn't it? You know the vessels we need, I finally realize are "flasks". There's plenty of aluminum ones with threaded mouths, but I wonder if they make SS.
Yes both can and vacuum cleaner pipe section are of aluminum and wouldn't hold up but the concept is there. If you spray methanol into it and cap the large end with the palm of your hand and light the tail end, it will bark very loudly, a crack-bang, near explosion, backfire type sound. It is a good shape for noise making.
Mark

stfx
Posts: 6
Joined: Thu Jul 29, 2004 10:26 pm
Antipspambot question: 0
Location: Canada

Post by stfx » Fri Jul 30, 2004 1:57 am

Well know that I know how to construct the exterior properly can you guys explain how to make the guts.

Mark
Posts: 10754
Joined: Sat Oct 11, 2003 10:14 pm

Post by Mark » Fri Jul 30, 2004 2:38 am

Here's some thermos bottles I cut out a few years ago. The one on the right is out of a one quart Aladdin thermos, it's nice stainless steel with stunning welds that couldn't look better. You could just as easily use one of these, I know you have a thermos you are debating on how to employ it best. Over ten years ago I saw plans for a pulsejet made from a an aerosol can and fence post for the exhaust tube. Any necking shape will do as long as it can take the heat and you have the desire.
My fuel additive Dynajet prototype I had planned on using to make a mold and try some casting experiments.
Mark
Attachments
040421105007.jpg
(583.47 KiB) Downloaded 1769 times

Mark
Posts: 10754
Joined: Sat Oct 11, 2003 10:14 pm

Post by Mark » Fri Jul 30, 2004 3:11 am

Mike Everman wrote:That additive can is aluminum though, isn't it? You know the vessels we need, I finally realize are "flasks". There's plenty of aluminum ones with threaded mouths, but I wonder if they make SS.
I bought one of these a year or so ago and it has a thread that fits a 3/8ths inch NPT pipe thread which is really closer to a half inch in reality. But anyway, I screwed a length of 3/8ths inch pipe on the end and made a miniature snorkeler. It also jam jars if you just pour in some methanol and light it jam jar style. I took the leather jacket off it.
And of course a larger stainless steel soap canister (Linen-n'-things) is also a good shape to work with. I recently posted some little booze flask that was shaped like a tiny military gas can and it was something that you could have made an Electra out of but only much smaller.


http://cgi.aol.ebay.com/ws/eBayISAPI.dl ... otohosting
Attachments
030120084543.jpg
(80.32 KiB) Downloaded 1434 times

Mark
Posts: 10754
Joined: Sat Oct 11, 2003 10:14 pm

Post by Mark » Fri Jul 30, 2004 3:24 am

Here's the potential "Jerry Electra" I was refering to.


http://cgi.aol.ebay.com/ws/eBayISAPI.dl ... otohosting

Mark

Attached is a long brass truck valve stem with the rubber buffed off, a 1/4" 32 thread spark plug and a laughing gas N20 cartridge I toyed with one day just to see if it would do much but the exhaust seems too narrow.
To the left is a reed and retainer and valve for a 1 inch diameter pipe jet. Just some dabbling that lead nowhere. I bought a special tap for the tire valve stems, I can't remember what the threading is offhand but those car valve stems of brass seem like good things to toy with being everywhere and cheap.
Attachments
030120163945.jpg
(231.41 KiB) Downloaded 1442 times

Mark
Posts: 10754
Joined: Sat Oct 11, 2003 10:14 pm

Post by Mark » Fri Jul 30, 2004 3:52 am

How about a Bat themed pulsejet? Something that plays upon the doppler frequencies bats use. I once read of two scientists arguing about their new found top secret doppler radar. One of them was adamant no bat could be doing all those calculatioins in his head, without even thinking about them. Of course radar uses electromagnetic energy but similarly, the delayed reflections of sound and sometimes two different sounds emitted and recieved, all this Mr. Bat does, all the math without even thinking about it. A bat sees "it" and the velocity in his head. The account was in the book "The Blind Watchmaker."
Mark

http://cgi.aol.ebay.com/ws/eBayISAPI.dl ... 70613&rd=1

stfx
Posts: 6
Joined: Thu Jul 29, 2004 10:26 pm
Antipspambot question: 0
Location: Canada

Post by stfx » Fri Jul 30, 2004 3:59 am

now that I understand the exterior i was wondering just how to put together the insides of it, like the reed valve (where to place it) and what other items I will need to construct the insides.

benny
Posts: 3
Joined: Fri Sep 10, 2004 12:21 am
Antipspambot question: 0
Location: Aus

Re: no-weld pulse jet

Post by benny » Sun Sep 12, 2004 6:54 am

Hey guys i am a jet-building newbie... Im a first year Uni student in Australia, with no metalwork skills whatso ever.. So this "no-weld" pulse jet really caught my eye, till i get more metalworking experience...

I was lookin @ Bruce Simpson's site http://www.aardvark.co.nz/pjet/noweld_pulsejet.shtml
and after hearing bad stories about cd's not showing up i dont feel comfortable ordering off him. What i was wondering was, did he cut the mouth towards the base in like 4 spots so he could fit the exhaust in the combustion chamber, and then clamp it? or did he cut the top of the flask off where the mouth was close in diameter to the diameter of the exhaust, and then somehow clamp it? How do you guys reccomend doing it? From what i can tell, he cut the base off the flask and fitted his own base, with holes drilled... what do u guys reccomend? also he just used a bit of copper pipe to inject his fuel, should there be some sort of nozzle on the end? Does hammering it so that there is some resistance do a good enough job?? What is the best and safest fuel to mess about with??

Another stupid sounding, fundamental question, is how do you stop the flame from reaching your LPG tank and going kablamo?

Where can i buy these fuel injectors, or jets from? as well as the lpg gas fittings (i plan on using either butane gas or LPG)...

thankyou so much for reading my post, and i hope this is the begining of my pulse-jetting hobby
noob in the house

Bruno Ogorelec
Posts: 3542
Joined: Sat Oct 04, 2003 7:31 am
Antipspambot question: 0
Location: Zagreb, Croatia

Re: no-weld pulse jet

Post by Bruno Ogorelec » Sun Sep 12, 2004 9:28 am

benny wrote:How do you stop the flame from reaching your LPG tank and going kablamo?
It won't. LPG will only burn in the presence of oxygen. So, the flame cannot travel through a pipe filled only with LPG, because there's no air to sustain combustion.

skyfrog
Posts: 539
Joined: Fri Jul 23, 2004 11:39 am
Antipspambot question: 0
Location: Kaohsiung, Taiwan
Contact:

Re: no-weld pulse jet

Post by skyfrog » Sun Sep 12, 2004 10:27 am

benny wrote:or did he cut the top of the flask off where the mouth was close in diameter to the diameter of the exhaust, and then somehow clamp it?
I am quite sure that it must have been several slits (not necessarily 4) made to the mouth, so as to hose-clip can be used to clamp the exhaust pipe. Otherwise hose-clip isn't strong enough to clamp slip-on pipes.
Long live jet engine !
Horace
Jetbeetle

benny
Posts: 3
Joined: Fri Sep 10, 2004 12:21 am
Antipspambot question: 0
Location: Aus

Re: no-weld pulse jet

Post by benny » Sun Sep 12, 2004 11:53 am

thanks boiz for the speedy replies... im somewhat comforted by knowin the tank wont go boom...

what about nozzles, etc for spraying LPG? what do i need or is an open pipe sufficient??? should i get the copper pipe like our dear mate uses, and crimp the ends with pliers?? Is it more efficient to have the injector on the "front" of the pulse jet where the valves are, or to plumb it in from the side? i guess for now the front is easier....

Thankyou so much for your help, im desperate to start building!
noob in the house

Post Reply